Melanocytic lesions
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Melanocytic lesions are commonly encountered in dermatopathology and an area which causes some difficulty, i.e. it is hard to decide in some cases whether a lesion is benign (e.g. Spitz nevus) or malignant (malignant melanoma).
Overview
Identifying melanocytes
- Clear or pigmented cytoplasm.
- +/-Nuclear pseudoinclusions.
- Epithelioid (superficial) or spindled (deep).
Benign lesions
| Name | Key feature | Microscopic | Clinical | Gross | Image | Ref. |
| Lentigo simplex | no nests, epidermis only | slender rete with melanocytes; no nests of melanocytes; no dermal melanocytes | < 40 years | small flat pigmented lesion | [1] | |
| Junctional melanocytic nevus | nests in epidermis | nests of melanocytes at tips of rete, no dermal melanocytes | usu. sun exposed skin, unusual in >50 years | small flat (uniformly) pigmented lesion | [1] | |
| Compound melanocytic nevus | benign nests in dermis & epidermis | nests of melanocytes at tips of rete and in dermis; dermal melanocytes lack nucleoli, lack mitoses and "mature with depth" -- see Note 1. | small slightly raised (uniformily) pigmented lesion | [2] | ||
| Intradermal melanocytic nevus | nested & individual melanocytes - only in dermis | nested & individual melanocytes - only in dermis, +/- multinucleation, +/-pseudovascular spaces | Clinical DDx: fibroepithelial polyp (skin tag), basal cell carcinoma | raised, non-pigmented lesion | [2] | |
| Spitz nevus (epithelioid and spindle-cell nevus) | long axis of nests perpendicular to surface, DE junction lesion | spindled, epithelioid or mixed melanocytes, long axis of nests perpendicular to surface, superficial mitoses common, +/-hyperkeratosis, +/-acanthosis, +/-hypergranulosis | Children & adolescents | usu. non-pigmented | Spitz nevus (drmihm.com), Spitz nevus - high mag. (WC), Spitz nevus - intermed. mag. (WC) | [2] |
| Pigmented spindle cell nevus of Reed (AKA Pigmented spindle cell nevus) | nests of heavily pigmented spindle cells, DE junction lesion | heavily pigmented spindle cells in epidermis & dermis, form "basket weave" pattern, well-circumscribed | women in teens & 20s; location: shoulder, pelvic girdle region | Pigmented +++, small size | Reed nevus - low mag. (WC), Reed nevus - intermed. mag. (WC), Reed nevus - collection (histopathology-india.net) | [3] |
| Blue nevus | lentil-shaped (ovoid) nests btw collagen bundles, dermal lesion | lentil-shaped nests, mix of spindle or dendritic or epithelioid cell morphology, nests btw collagen | usu. head & neck or extremities; clinically confused with melanoma[4] | blue flat or slightly raised lesion | Blue nevus (WC), Blue nevus - very low mag. (WC), Blue nevus - intermed. mag. (WC) | [5] |
| Cellular blue nevus | dermal lesion with pigmented spindle cells & epithelioid cells | deep dermis +/-subcutis extension; cells lack nucleoli; biphasic: (1) epithelioid cells with pale cytoplasm, (2) pigmented spindle cells +/- melanophages | congenital or acquired; usu. scalp or butt | blue flat or raised lesion | [5] | |
| Congenital-pattern nevus | growth along dermal structures | extend along dermal structures (e.g. nerves, hair shafts, ducts); lacks atypia; +/-mitoses | congenital or acquired; large ones increased melanoma risk[6] | small, intermediate (2-20 cm) or large | [5] | |
| Dysplastic nevus (Clark's nevus) | melanocyte bridges, lamellar fibrosis | melanocytes "bridges" between sides of rete ridges, "lamellar fibrosis" (collagen deep to epidermis), mod. atypia | may be familial - precursor to melanoma | may have asymmetry in shape or pigmentation | Dysplastic nevus - low mag., Dysplastic nevus - high mag. | [7] |
| Halo nevus | lymphocytes +++ | lymphocytes at perimeter of melanocytic; epidermal melanocytes not nested; may be dermal, epidermal or both | central zone of pigment | [7] |
Note 1:
- "Maturation" in the context of melanocytic lesions means (1) the cells get smaller with depth, (2) cells are less mitotic with depth.
Melanocytic nevus
General
- Benign.
- Think melanoma.
- In common language: mole.
Clinical:
- ABCD = asymmetric, borders (irregular), colour (black), diameter (large).
Microscopic
Features:
- Symmetrical lesion.
- "Matures" with depth
- Less cellular with depth
- Less nuclear atypia with depth.
- Smaller cells with depth.
- Smaller nests with depth.
- Rare mitoses (superficial).
- No deep mitoses.
- No destruction of surrounding structures.
- No nucleoli.
Subtypes
Compound melanocytic nevus
- In the dermis and epidermis - key feature.
Junctional melanocytic nevus
- In the epidermis - key feature.
Intradermal melanocytic nevus
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SKIN, PUNCH BIOPSY: - INTRADERMAL MELANOCYTIC NEVUS.
Congenital-pattern nevus
- AKA congenital nevus.
General
- Congenital or acquired - thus "congenital-pattern".
- Large ones increase melanoma risk.[6]
- Small (<2 cm), intermediate (2-20 cm), large (>20 cm).
Microscopic
Features:[5]
- Growth along dermal structures - key feature.
- Nerves, hair shafts, ducts.
- Lacks nuclear atypia.
- +/-Mitoses.
Recurrent melanocytic nevus
General
- Classically, arises at the site of a partially excised nevus.[8]
Microscopic
Features - three layers (often described as a "sandwich"):
- Features of a compound nevus or junctional nevus.
- Scar.
- Thick collagen bundles arranged parallel to the skin surface.
- Features of an intradermal nevus.
May have:[8]
- Pagetoid spread of melanocytes.
- Confluent nests at the DE junction.
- Nuclear atypia - uncommon.
DDx:[8]
- Melanoma in situ - classically spread beyond the scar, unlike pseudomelanoma - growth confined to epidermis.
IHC
- HMB-45 deep component -ve.
- Ki-67 - non-proliferative.
Sclerosing melanocytic nevus
- AKA sclerosing nevus.
General
- Similar to recurrent nevus.
- Clinically may be confused with melanoma.
- No history of trauma or prior excision.
Microscopic
Features:[9]
- Trizonal - may be described as a sandwich:
- Junctional or compound nevus.
- Fibrotic tissue with irregular melanocytic nests.
- Nevus below scar.
DDx:
- Malignant melanoma.
- Recurrent melanocytic nevus - also trizonal; however, has a fibrotic layer that does not have melanocytes in it.[9]
Pigmented spindle cell nevus
- AKA pigmented spindle cell nevus of Reed.
General
- Uncommon.
- Women in teens & 20s.
- Location: shoulder, pelvic girdle region.
Microscopic
Features:[3]
- Nests of heavily pigmented spindle cells at dermal-epidermal junction - key feature.
- Nevoid cells in epidermis & dermis - form "basket weave" pattern
- Well-circumscribed lesion.
Notes:
- No epithelioid nevus cells.
DDx:
Images:
Spitz nevus
- AKA epithelioid and spindle-cell nevus.
General
- May be very difficult to differentiate from melanoma.
Epidemiology:
- Children & adolescents.
Treatment:
- Complete excision.[10]
Gross
- Usually face or extremity.[11]
Microscopic
Features:[2]
- Architecture:
- Nests of cells (spindle, epithelioid or spindle/epithelioid) - in both dermis and epidermis.
- Nests are vertically arranged, i.e. the long axis of the nests are perpendicular to the skin surface.
- Nest arrangement/orientation described as "cluster of bananas".
- Nests are vertically arranged, i.e. the long axis of the nests are perpendicular to the skin surface.
- Nests of cells (spindle, epithelioid or spindle/epithelioid) - in both dermis and epidermis.
- +/-Hyperkeratosis (more keratin, i.e. thick stratum corneum).
- +/-Hypergranulosis (thick stratum granulosum).
- +/-Acanthosis (thick stratum spinosum).
- Kamino bodies (also written Camino bodies) - dense eosinophilic bodies.[12]
- Apoptotic cells.
- Kamino bodies are rare in melanoma.
Notes:
- Never in the setting of solar elastosis.[13]
- If there is solar elastosis -- it's melanoma.
DDx:
Images:
Blue nevus
- Common blue nevus redirects here.
- Abbreviated BN.
General
- Usually head & neck, extremities (e.g. dorsum of wrist or foot) or buttock.[14]
- Clinically confused with malignant melanoma.[4]
Clinical:
- Blue flat or slightly raised lesion.
Microscopic
Features:[5]
- Lentil-shaped (ovoid) nests between collagen bundles.
- Mix of spindle or dendritic or epithelioid cell morphology.
Notes:[15]
- No epidermal component.
- May be assoc. with a hair follicle.
DDx:
- Dermatofibroma - esp. amelanotic BN.
- Malignant melanoma.
- Clear cell sarcoma.
Images:
Variants of blue nevus
Several histologic variants:[15]
- Common blue nevus - the blue nevus not otherwise specified.
- Cellular blue nevus.
- Amelanotic blue nevus - may be confused with a dermatofibroma.
- Sclerosing blue nevus - has stromal fibrosis.
- Epithelioid blue nevus.
Memory device:
- C CASE = Common, Cellular, Amelanotic, Sclerosing, Epithelioid.
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SKIN LESION, RIGHT WRIST DORSUM, PUNCH BIOPSY: - COMMON BLUE NEVUS.
SKIN LESION, LEFT SHIN, PUNCH BIOPSY: - SCLEROSING BLUE NEVUS.
Cellular blue nevus
General
- Congenital or acquired.
- Usually scalp or butt.
- Variant of the common blue nevus.
Microscopic
Features:[5]
- Dermal lesion with pigmented spindle cells & epithelioid cells - key feature.
- Cells lack nucleoli.
- Biphasic:
- Epithelioid cells with pale cytoplasm.
- Pigmented spindle cells +/- melanophages.
Images:
Acral nevus
- AKA melanocytic nevus with intraepidermal ascent of cells (MANIAC).
General
- Palms or soles.
Microscopic
Features:
- Nevus with intraepidermal ascent of cells.
Notes:
- Intraepidermal ascent of cells is usually suggestive of melanoma.
- In acral sites the criteria are relaxed, i.e. this is considered benign for this site.
Dysplastic melanocytic nevus
General
- Benign.
- Dysplastic nevi are considered a risk factor for melanoma and may be a precursor of melanoma, as the name dysplastic nevus suggests.[16]
- Most melanoma cases do not have evidence of a pre-existing (dysplastic) nevus.[17]
- Large numbers of these nevi (10-100) are seen in dysplastic nevus syndrome.[18]
- Individuals with this syndrome have an increased risk of melanoma and approximately one third of their melanomas arise from a Clark nevus. The other two thirds arise de novo.
Clinical:[19]
- Associated with sun exposure.
Treatment:
- Clark nevi with severe nuclear atypia are treated like melanoma.
Gross
Features:[19]
- "Ugly duckling sign" - lesion looks different than the rest.
- ABCDE criteria of in melanoma.
Microscopic
Features:[7]
- Melanocytes "bridges" between sides of rete ridges.
- Drapping fibrous tissue - "lamellar fibrosis" - collagen deep to epidermis.
- Usually moderate nuclear atypia (small nucleoli present) - see grading section.
- Junctional component (cells in the epidermis at the DE junction) larger than the intradermal component - shoulder phenomenon.
DDx:
Images:
- Dysplastic nevus - low mag. (WC).
- Dysplastic nevus - intermed. mag. (WC).
- Dysplastic nevus - high mag. (WC) - shows bridging and lamellar fibrosis.
- Dysplastic nevus - very high mag. (WC) - shows bridging and lamellar fibrosis.
Grading
These lesions are usually graded:[20]
| Grade | Size of nucleus | Other features |
|---|---|---|
| Mild | 1x keratinocyte nucleus | no nucleoli/very small nucleoli †,[21] slight hyperchromasia |
| Moderate | 1-2x keratinocyte nucleus | small nucleoli †, irregular nuclear contours |
| Severe | >2x keratinocyte nucleus | prominent nucleoli †‡ |
† The sizes "very small", "small" and "prominent" are not defined; it is suggested that "very small" is visible with the 40x objective, "small" with the 20x objective and "prominent" with the 10x objective. Focal, rare small nucleoli are not significant; they can be seen in benign melanocytic nevi.
‡ Prominent nucleoli (alone) is considered enough to call "severe".[20]
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SKIN, LOWER BACK, EXCISION: - DYSPLASTIC MELANOCYTIC NEVUS WITH MILD NUCLEAR ATYPIA. - NEAREST MARGIN (LATERAL MARGIN) 6 MM.
Micro
The sections show hair-bearing skin with a compound melanocytic lesion. The epidermal component extends at least three rete ridges further than the dermal component (shoulder phenomenon). There is bridging between the sides of the rete ridges and lamellar fibrosis. The melanocyte nuclei are approximately the size of the keratinocyte nuclei, and do not have a prominent nucleolus (mild nuclear atypia).
There is no upward scatter of melanocytes and melanocytes in the dermis are mature. No mitotic activity is appreciated.
Neurocristic hamartoma
Main article: Neurocristic hamartoma
Desmoplastic melanocytic nevus
- AKA sclerosing melanocytic nevus.
General
- Benign.
Gross
- Usu. "small" and symmetric.
Clinical DDx:
Microscopic
Features:[22]
- Compound nevus or intradermal nevus with prominent dermal fibrosis.
- Fibrosis: extra pink - versus surrounding.
DDx:
IHC
Features:[22]
- Melan A (MART-1) +ve (not usu. +ve in desmoplastic melanoma).[22]
- S-100 +ve.
- Ki-67 -- only rare cells.
See also
References
- ↑ 1.0 1.1 Humphrey, Peter A; Dehner, Louis P; Pfeifer, John D (2008). The Washington Manual of Surgical Pathology (1st ed.). Lippincott Williams & Wilkins. pp. 498. ISBN 978-0781765275.
- ↑ 2.0 2.1 2.2 2.3 Humphrey, Peter A; Dehner, Louis P; Pfeifer, John D (2008). The Washington Manual of Surgical Pathology (1st ed.). Lippincott Williams & Wilkins. pp. 499. ISBN 978-0781765275.
- ↑ 3.0 3.1 Humphrey, Peter A; Dehner, Louis P; Pfeifer, John D (2008). The Washington Manual of Surgical Pathology (1st ed.). Lippincott Williams & Wilkins. pp. 500. ISBN 978-0781765275.
- ↑ 4.0 4.1 Mitchell, Richard; Kumar, Vinay; Fausto, Nelson; Abbas, Abul K.; Aster, Jon (2011). Pocket Companion to Robbins & Cotran Pathologic Basis of Disease (8th ed.). Elsevier Saunders. pp. 592. ISBN 978-1416054542.
- ↑ 5.0 5.1 5.2 5.3 5.4 5.5 Humphrey, Peter A; Dehner, Louis P; Pfeifer, John D (2008). The Washington Manual of Surgical Pathology (1st ed.). Lippincott Williams & Wilkins. pp. 501. ISBN 978-0781765275.
- ↑ 6.0 6.1 Kumar, Vinay; Abbas, Abul K.; Fausto, Nelson; Aster, Jon (2009). Robbins and Cotran pathologic basis of disease (8th ed.). Elsevier Saunders. pp. 1170. ISBN 978-1416031215.
- ↑ 7.0 7.1 7.2 Humphrey, Peter A; Dehner, Louis P; Pfeifer, John D (2008). The Washington Manual of Surgical Pathology (1st ed.). Lippincott Williams & Wilkins. pp. 502. ISBN 978-0781765275.
- ↑ 8.0 8.1 8.2 Busam, Klaus J. (2009). Dermatopathology: A Volume in the Foundations in Diagnostic Pathology Series (1st ed.). Saunders. pp. 465. ISBN 978-0443066542.
- ↑ 9.0 9.1 Fabrizi, G.; Pennacchia, I.; Pagliarello, C.; Massi, G. (Nov 2008). "Sclerosing nevus with pseudomelanomatous features.". J Cutan Pathol 35 (11): 995-1002. doi:10.1111/j.1600-0560.2007.00941.x. PMID 18537860.
- ↑ Gelbard, SN.; Tripp, JM.; Marghoob, AA.; Kopf, AW.; Koenig, KL.; Kim, JY.; Bart, RS. (Aug 2002). "Management of Spitz nevi: a survey of dermatologists in the United States.". J Am Acad Dermatol 47 (2): 224-30. PMID 12140468.
- ↑ Busam, Klaus J. (2009). Dermatopathology: A Volume in the Foundations in Diagnostic Pathology Series (1st ed.). Saunders. pp. 449. ISBN 978-0443066542.
- ↑ Kirkwood, John M.; Jukic, Drazen; Averbook, Bruce J.; Sender, Leonard S. (October 2009). "Melanoma in Pediatric, Adolescent, and Young Adult Patients". Semin Oncol. 36 (5): 419-31. PMC 2797485. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2797485/.
- ↑ Jakubovic, H. 16 July 2010.
- ↑ Busam, Klaus J. (2009). Dermatopathology: A Volume in the Foundations in Diagnostic Pathology Series (1st ed.). Saunders. pp. 456. ISBN 978-0443066542.
- ↑ 15.0 15.1 Busam, Klaus J. (2009). Dermatopathology: A Volume in the Foundations in Diagnostic Pathology Series (1st ed.). Saunders. pp. 457. ISBN 978-0443066542.
- ↑ Rezze, GG.; Leon, A.; Duprat, J. (Dec 2010). "Dysplastic nevus (atypical nevus).". An Bras Dermatol 85 (6): 863-71. PMID 21308311.
- ↑ Longo, C.; Rito, C.; Beretti, F.; Cesinaro, AM.; Piñeiro-Maceira, J.; Seidenari, S.; Pellacani, G. (Sep 2011). "De novo melanoma and melanoma arising from pre-existing nevus: in vivo morphologic differences as evaluated by confocal microscopy.". J Am Acad Dermatol 65 (3): 604-14. doi:10.1016/j.jaad.2010.10.035. PMID 21715047.
- ↑ Online 'Mendelian Inheritance in Man' (OMIM) 155600
- ↑ 19.0 19.1 Dediol, I.; Bulat, V.; Zivković, MV.; Marković, BM.; Situm, M. (Sep 2011). "Dysplastic nevus--risk factor or disguise for melanoma.". Coll Antropol 35 Suppl 2: 311-3. PMID 22220461.
- ↑ 20.0 20.1 Busam, Klaus J. (2009). Dermatopathology: A Volume in the Foundations in Diagnostic Pathology Series (1st ed.). Saunders. pp. 447-8. ISBN 978-0443066542.
- ↑ Arumi-Uria, M.; McNutt, NS.; Finnerty, B. (Aug 2003). "Grading of atypia in nevi: correlation with melanoma risk.". Mod Pathol 16 (8): 764-71. doi:10.1097/01.MP.0000082394.91761.E5. PMID 12920220.
- ↑ 22.0 22.1 22.2 Busam, Klaus J. (2009). Dermatopathology: A Volume in the Foundations in Diagnostic Pathology Series (1st ed.). Saunders. pp. 464. ISBN 978-0443066542.